1. Field of the Invention
The present invention relates to an apparatus for and a method of hot baking of photoresist prior to the dry plasma etch of a semiconductor process.
2. Description of the Background Art
Referring to FIG. 1, a wafer carrier 30 is loaded with one or a plurality of semiconductor wafers 20 and is placed in the hot bake chamber 10 on the carrier transport 40 through the chamber lock 50. The hot plate 60 is activated such that the semiconductor wafer 20 is brought to a temperature sufficient to allow any moisture to be driven from the photoresist mask that has been deposited on the semiconductor wafers 20. The temperature is approximately 120xc2x0 C. for a period of approximately 90 seconds. Once the moisture has been driven from the photoresist, the hot plate 60 is deactivated and the chamber lock 55 is opened. The wafer carrier is moved from the hot bake chamber 10 into the load and lock chamber 70 by the activation of motors (not shown) attached to the carrier transports 40 and 80. The chamber locks 55 and 75 are sealed and the load and lock chamber 70 is evacuated to a high degree by a vacuum pump (not shown) attached to the exhaust valves 100. Once sufficient vacuum has been achieved, exhaust valves 100 are closed and the inlet valves 90 are opened to allow nitrogen (N2) to be pumped into the load and lock chamber 70. After a sufficient level of N2 has been achieved, the inlet valves 90 are closed, the exhaust valves 100 are opened, and the N2 is evacuated from the load and lock chamber 70. Chamber lock 75 is then opened and the motors (not shown) for the carrier transports 80 and 120 are activated to move the wafer carriers 30 containing the semiconductor wafers 20 from the load and lock chamber 70 to the Dry Plasma Etch Chamber 110. In the Dry Plasma Etch Chamber 110, the surface of the semiconductor wafers 20 are etched.
In U.S. Pat. No. 5,380,682 (Issued Jan. 10, 1995 to Edwards, et al. for xe2x80x9cWafer Processing Cluster Tool Batch Preheating and Degassing Methodxe2x80x9d) teaches a technique for the preparation of semiconductor wafers for processing by preheating the wafers to a high temperature to drive out gas contaminants on the surface of the semiconductor wafers.
In U.S. Pat. 5,407,867 (issued Apr. 18, 1995 to Iwasaki, et al. for xe2x80x9cMethod Of Forming A Thin Film On Surface Of Semiconductor Substratexe2x80x9d) Illustrates a technique for the removal of natural oxides and contaminants from the surface of semiconductor substrates and then depositing a thin film material upon the semiconductor substrate.
An object of the invention is an apparatus to hot bake the photoresist deposited upon a semiconductor wafer in the loading chamber prior to a plasma dry etch process. The purpose of the hot bake is the removal of moisture from the photoresist.
This apparatus is comprising a chamber in which a wafer carrier containing one or more semiconductor wafers is placed through an entrance lock; a heating source such as a heating plate or high intensity light source to bake the moisture from the photoresist; an exhaust valving system coupled to a vacuum pump to evacuate the chamber; an inlet valving system coupled to a source of N2 to fill the chamber with N2; and an exit lock to allow the carrier transport to move the carrier to the plasma dry etch chamber.